This invention relates to an air-liquid cooled engine and more particularly to an improved cooling system for an engine utilized to power a vehicle.
Internal combustion engines are, as is widely known, employed for propelling a wide variety and type of vehicles. One such type of vehicle powered by an internal combustion engine is a small motor scooter. Such motor scooters usually employ a body surround for providing a neat shape to the scooter and for protection of its mechanical components. Of course, when the engine is provided within such a body, it is necessary to employ a cooling system for cooling the engine.
Normally, such cooling systems require the use of a fan due to the enclosed configuration of the body. In order to provide more efficient cooling and to insure adequate cooling, it has been a practice to employ liquid cooled internal combustion engines in this application wherein a cooling fan is supplied for circulating air across the radiator which conveys and discharges the heat from the engine. However, this type of cooling system has some disadvantages.
Specifically, if the entire engine is liquid cooled, this is not always desirable. The reason for this is that it is preferred to operate the cylinder barrel at a higher temperature than the cylinder head in which the intake manifold or at least a portion of the intake manifold passages are formed. The reason for this is that it is desirable not to heat significantly the induction charge because this reduces the volumetric efficiency of the engine. On the other hand, if the cylinder barrel is cooled too greatly, then frictional losses become high.
It is, therefore, a principal object of this invention to provide an improved air-liquid cooled engine which can be utilized for a wide variety of applications including powering of motor vehicles.
It is a further object of this invention to provide a cooling system for an internal combustion engine wherein the cylinder may be operated at a higher temperature than the cylinder head.
Although cooling systems have been proposed that include air cooled cylinder barrels and water cooled cylinder heads, such systems are not particularly compact and can become quite complicated. It is, therefore, another object of this invention to provide an improved and simplified arrangement for an airliquid cooled internal combustion engine.